Expansion valve, heat pump type refrigeration cycle apparatus, and air handling unit

ABSTRACT

A first expansion valve is provided in an outdoor unit, and a second expansion valve is provided in an indoor unit. A pipe line connects a first joint pipe of the first expansion valve and a second joint pipe of the second expansion valve. When a refrigerant flows in from the second joint pipe and flows out from the first joint pipe, the first and second expansion valves are in a full open state due to pressure of the refrigerant. When the refrigerant flows in from the first joint pipe and flows out from the second joint pipe, the first and second expansion valves are in semi-closed state (flow rate controlling state). In a cooling mode, the second expansion valve expands the refrigerant just before an indoor heat exchanger, and in a heating mode, the first expansion valve expands the refrigerant just before an outdoor heat exchanger. In both heating and cooling mode, a large amount of refrigerant flows through the pipe line to reduce pressure loss.

REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 12/402,134 filed Mar. 11, 2009 which is a Continuation-in-Partof U.S. patent application Ser. No. 12/128,933 filed May 29, 2008 andclaims the benefit of Japanese Patent Application No. 2008-332324 filedon Dec. 26, 2008.

BACKGROUND

1. Field of the Invention

The present invention relates to an expansion valve for controlling aflow rate of a refrigerant in a first flow direction of the refrigerantand for discharging the refrigerant in a second flow direction, a heatpump type refrigeration cycle apparatus using the expansion valve, andan air handling unit having the heat pump type refrigeration cycleapparatus.

2. Description of the Related Art

Conventionally, in the heat pump type refrigeration cycle apparatus, anexpansion valve is interposed between an outdoor heat exchanger and anindoor heat exchanger. In a cooling mode, a refrigerant from the outdoorheat exchanger is expanded by the expansion valve and guided to theindoor heat exchanger. In a heating mode, the refrigerant from theindoor heat exchanger is expanded by the expansion valve and guided tothe outdoor heat exchanger. Various expansion valves to control the flowrate of the refrigerant for adapting to normal operation, defrostingoperation, and dehumidifying operation are proposed (for example,Japanese Patent Application Unexamined Publication No. 2000-266194 andJapanese Patent Application Examined Publication No. H6-65915).

Incidentally, in many heat pump type refrigeration cycle apparatuses,the expansion valve is provided at the outdoor heat exchanger (outdoorunit) side. In this case, the refrigerant expanded by the expansionvalve flows into the indoor heat exchanger via a long pipe line.Therefore, there is a problem that the expanded refrigerant is subjectto pressure loss, and flow rate control by the expansion valve isdifficult. The same is true in a case that the expansion valve isprovided at the indoor heat exchanger side.

Accordingly, an object of the present invention is to provide anexpansion valve to control the flow rate at the indoor heat exchanger inthe cooling mode, and to control the flow rate at the outdoor heatexchanger in the heating mode, and a heat pump type refrigeration cycleapparatus using the expansion valve.

SUMMARY

In accordance with at least one presently preferred implementation,there is provided an expansion valve for controlling a flow rate of arefrigerant in a first flow direction of the refrigerant and fordischarging the refrigerant in a second flow direction,

the expansion valve including:

a valve housing having a first port communicating with a cylindricalmain valve chamber and with a side part of the main valve chamber, and asecond port communicating with an end of the main valve chamber in anaxial direction thereof;

a piston-shaped valve seat slidably disposed in the main valve chamberin the axial direction of the main valve chamber, and having a sub valvechamber opposed to the second port in the main valve chamber, a valveport for connecting the sub valve chamber to the second port, and aconnecting hole for always connecting the sub valve chamber to the firstport;

a valve plug for opening and closing the valve port of the valve seat bymoving relative to the valve seat in the axial direction; and

a driving member for driving the valve plug in the axial direction,

wherein in a case that the first port is under high refrigerant pressureand the second port is under low refrigerant pressure, a flow rate ofthe refrigerant flowing from the sub valve chamber through a pathbetween the valve plug and the valve port is controlled by closing thesecond port with the valve seat seated around the second port due todifferential pressure between the first and second ports and bycontrolling a position of the valve plug in the axial direction with thedriving member, and

wherein in a case that the first port is under low refrigerant pressureand the second port is under high refrigerant pressure by making therefrigerant flow reversely, the refrigerant is discharged to the firstport via the second port and the main valve chamber, said second port isopened by moving the valve plug in the axial direction with the drivingmember and by separating the valve seat from the second port due to thedifferential pressure between the second and first ports.

Preferably, the valve seat is a piston type member of which bottom wallat the second port side is a tapered wall, and the connecting hole isprovided at a side of the valve seat.

Preferably, the valve seat is composed of a circular disk on which thevalve port is formed, and a plurality of guiding board formed at anouter periphery of the circular disk, and slidingly contact an inside ofthe main valve chamber, and the connecting holes are formed between theadjacent guiding walls.

Preferably, the driving member is composed of a rotor case fixed aroundan opening of the valve housing opposite to the first port to form acylindrical rotor chamber, a rotor having a rotor shaft in the axialdirection of the rotor chamber and the main valve chamber and rotatablyand movably disposed in the rotor chamber in the axis direction, and astator coil attached to an outer circumference of the rotor case anddriving the rotor, and the valve body is disposed at the rotor shaftnear the valve seat, said driving member further including a supportingmember fixed to the opening of the valve housing for separating the mainvalve chamber from the rotor chamber and for supporting the rotor shaftof the rotor, and configured to control an opening of the valve port bymoving the rotor and the rotor shaft in the axial direction with a screwmechanism of the supporting member and the rotor shaft using a rotationof the rotor, and configured to equalize the pressure between the mainvalve chamber and the rotor chamber when the rotor is moved in the axialdirection using a pressure equalizing path communicating with the mainvalve chamber and the rotor chamber,

wherein the supporting member includes: a fitting part for fitting intothe opening of the valve housing; and a flange part fixed to an endaround the circumference of the opening of the valve housing,

wherein a communicating path opening at the rotor chamber side is formedon the flange, and an outer diameter of the fitting part is a specificamount smaller than an inner diameter of an inner circumference of thevalve housing,

wherein a concave part concaved in a radial direction perpendicular tothe axial direction is formed on the fitting part at the flange side,and a gap between the outer circumference of the fitting part and theinner circumference of the valve housing communicates with thecommunicating path via the concave part, and

wherein the pressure equalizing path is composed of the gap between theouter circumference of the fitting part and the inner circumference ofthe valve housing and the communicating path.

According to another aspect of the present invention, there is provideda heat pump type refrigeration cycle apparatus in which a cooling modeand a heating mode is switched by reversing a flow direction ofrefrigerant,

the refrigeration cycle apparatus including:

two of the above-described expansion valves consisting of first andsecond expansion valves, and interposed between an indoor heat exchangerand an outdoor heat exchanger,

wherein first ports of the expansion valves are connected to each othervia a pipe line, and

wherein a second port of the first expansion valve is connected to theoutdoor heat exchanger at the outdoor heat exchanger side, and a secondport of the second expansion valve is connected to the indoor heatexchanger at the indoor heat exchanger side.

According to another aspect of the present invention, there is providedan air handling unit having the above-described heat pump typerefrigeration cycle apparatus,

wherein the first expansion valve is disposed in an outdoor unittogether with the outdoor heat exchanger, and the second expansion valveis disposed in an indoor unit together with the indoor heat exchanger.

These and other objects, features, and advantages of the presentinvention will become more apparent upon reading of the followingdetailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a heat pump type refrigeration cycleapparatus according to a first embodiment of the present invention;

FIG. 2 is a vertical sectional view showing an expansion valve in aclosed state according to the first embodiment of the present invention;

FIG. 3 is a vertical sectional view showing the expansion valve in afully open state;

FIGS. 4A and 4B are schematic views showing a positional relationshipbetween a valve plug and a valve seat when a flow rate of the expansionvalve is controlled;

FIGS. 5A and 5B are schematic views showing a positional relationshipbetween the valve plug and the valve seat when the expansion valve isfully open;

FIG. 6 is a vertical section view showing the closed compaction valve 10according to a second embodiment;

FIG. 7 is a vertical section view showing the opened compaction valve 10according to the second embodiment;

FIG. 8 is a section view taken on line P-P of FIG. 7;

FIG. 9 is a perspective view showing the valve seat of the compactionvalve 10 according to the second embodiment;

FIGS. 10A, 10B, and 10C are a partially broken side view, a bottom view,and a perspective view showing a supporting member as a first example ofthe expansion valve according to the second embodiment;

FIG. 10D is a sectional view showing a valve housing;

FIGS. 11A and 11B are a partially broken side view and a bottom viewshowing a supporting member as a second example of the expansion valveaccording to the second embodiment;

FIGS. 12A and 12B are a partially broken side view and a bottom viewshowing a supporting member as a third example of the expansion valveaccording to the second embodiment; and

FIGS. 13A and 13B are a partially broken side view and a bottom viewshowing a supporting member of a conventional expansion valve.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Embodiments of an expansion valve, a heat pump type refrigeration cycleapparatus, and an air handling unit will be explained with reference tofigures.

As shown in FIG. 1, a first expansion valve 10 ₁ is mounted on anoutdoor unit 100, and a second expansion valve 10 ₂ is mounted on anindoor unit 200. Further, an outdoor heat exchanger 20 is mounted on theoutdoor unit 100, and an indoor heat exchanger 30 is mounted on theindoor unit 200. A flow path switching valve 40 and a compressor 50 aremounted on the outdoor unit 100. The expansion valves 10 ₁, 10 ₂, theoutdoor heat exchanger 20, the indoor heat exchanger 30, the flow pathswitching valve 40 and the compressor 50 are connected as shown in FIG.1, and compose the heat pump type refrigeration cycle apparatus.Incidentally, an accumulator, a pressure sensor, a thermal sensor andthe like are not shown in FIG. 1.

The flow path switching valve 40 switches the flow path of therefrigeration cycle apparatus to a cooling mode or a heating mode. Inthe cooling mode as indicated by a solid-line arrow in FIG. 1, therefrigerant compressed by the compressor 50 flows from the flow pathswitching valve 40 to the outdoor heat exchanger 20, then flows via thefirst expansion valve 10 ₁ and the pipe line “a” to the second expansionvalve 10 ₂. Then, the refrigerant is expanded by this second expansionvalve 10 ₂ and flows to the indoor heat exchanger 30. The refrigerantflowing into the indoor heat exchanger 30 flows into the compressor 50via the flow path switching valve 40. On the other hand, in the heatingmode as indicated by a dashed-line arrow in FIG. 1, the refrigerantcompressed by the compressor 50 flows from the flow path switching valve40 into the indoor heat exchanger 30, then flows via the secondexpansion valve 10 ₂ and the pipe line “a” to the first expansion valve10 ₁. Then, the refrigerant is expanded by this first expansion valve 10₁ and circulates to the outdoor heat exchanger 20, the flow pathswitching valve 40, and the compressor 50 sequentially.

The expansion valves 10 ₁, 10 ₂ are in a later-described fully openstate not to control the flow rate of the refrigerant, or in asemi-closed state to control the flow rate of the refrigerant. In thefully open state, the refrigerant flows in from a later described jointpipe 12 a at a side “A” and flows out to a joint pipe 11 a at a side“B”. Further, in the semi-closed state, the refrigerant flows in fromthe joint pipe 11 a at a side “B” and flows out to the joint pipe 12 aat a side “A”. Namely, in the cooling mode, the first expansion valve 10₁ is in the fully open state, and the second expansion valve 10 ₂ is inthe semi-closed state. Further, in the heating mode, the secondexpansion valve 10 ₂ is in the fully open state, and the first expansionvalve 10 ₁ is in the semi-closed state. Accordingly, in the coolingmode, the outdoor heat exchanger 20 works as a condenser, and the indoorheat exchanger 30 works as an evaporator to cool a room interior.Further, in the heating mode, the outdoor heat exchanger 20 works as theevaporator, and the indoor heat exchanger 30 works as the condenser toheat the room interior.

Further, in the cooling mode, the second expansion valve 10 ₂ expandsthe refrigerant just before the indoor heat exchanger 30, and in theheating mode, the first expansion valve 10 ₁ expands the refrigerantjust before the outdoor heat exchanger 20. In both the cooling andheating mode, a large amount of refrigerant flows through the pipe line“a” connecting the first expansion valve 10 ₁ and the second expansionvalve 10 ₂. Therefore, pressure loss before the expansion valve having aflow rate control function is reduced, and running performance isimproved.

Next, the first expansion valve 10 ₁ and the second expansion valve 10 ₂according to a first embodiment will be explained with reference toFIGS. 2 and 3.

As shown in FIGS. 2 and 3, each of the first expansion valve 10 ₁ andthe second expansion valve 10 ₂ (hereafter referred to as expansionvalve 10) includes a valve housing 1. A cylindrical main valve chamber1A, a first port 11 opened at an inner periphery of the main valvechamber 1A, and a second port 12 opened at an end of the main valvechamber 1A in a direction of an axis L1 are formed on the valve housing1. The joint pipes 11 a, 12 a are respectively attached to the firstport 11 and the second port 12.

A valve seat 2 is provided in the main valve chamber 1A. The valve seat2 includes a large diameter part 21 having a large diameter about theaxis L1 of the main valve chamber 1A, and a small diameter part 22. Aninside of this small diameter part 22 is a sub valve chamber 2A.Further, a valve port 23 for connecting the sub valve chamber 2A to thesecond port 12, and a plurality of high pressure inlets 24 as connectingholes for constantly connecting the sub valve chamber 2A to the firstport 11 are formed on the small diameter part 22. The valve seat 2 isformed in a piston shape. An outer periphery of the large diameter part21 slidably abuts on the inner periphery of the main valve chamber 1A.The valve seat 2 slides on the main valve chamber 1A in the axis L1direction. A relationship between a capacity coefficient C₂₄ of a valveof the high pressure inlets 24 and a capacity coefficient C₂₃ of a valveof the valve port 23 is C₂₄>C₂₃. Therefore, as described later, when thesecond port 12 is in high pressure, a differential pressure between thesecond port 12 and the sub valve chamber 2A separates the valve seat 2from the second port 12.

A support member 3 is fixed to an upper side of the valve housing 1 witha fixing bracket 31. A long guiding hole 32 is formed on the supportmember 3 in the axis L1 direction. A cylindrical valve holder 4 isslidably fitted into the guiding hole 32 in the axis L1 direction. Thus,the valve holder 4 is movable relative to the valve housing 1 via thesupport member 3 in the axis L1 direction.

The valve holder 4 is coaxially arranged with the main valve chamber 1A.A valve plug 5 of which end is formed in a needle shape is fixed to abottom of the valve holder 4 at the sub valve chamber 2A side. When thevalve plug 5 and the valve holder 4 are moved in the sub valve chamber2A of the valve seat 2 in the axis L1 direction, an opening space of thevalve port 23 is increased or decreased. Thus, the flow rate of therefrigerant flowing from the first port 11 to the second port 12 iscontrolled. Incidentally, the valve plug 5 is movable in between a fullyclosed position as shown in FIG. 2 and a full open position as shown inFIG. 3.

The valve holder 4 is engaged with a rotor shaft 61 of a stepping motor6 as a later-described driving member. Namely, a flange 61 a isintegrally formed on a lower end 61A of the rotor shaft 61. This flange61 a and an upper end of the valve holder 4 hold a washer 41. The lowerend 61A of the rotor shaft 61 is rotatably engaged with the upper end ofthe valve holder 4. Owing to this engagement, the valve holder 4 isrotatably suspended by the rotor shaft 61. A spring bracket 42 ismovably provided in the valve holder 4 in the axis L1 direction. Acompression spring is provided in between the spring bracket 42 and thevalve plug 5 under a predetermined load. Thus, the spring bracket 42 ispushed upward to abut on the lower end 61A of the rotor shaft 61.

A male thread 61 b is formed on the rotor shaft 61. This male thread 61b is screwed into a female thread 3 a formed on the support member 3.Thus, as the rotor shaft 61 is rotated, the rotor shaft 61 is moved inthe axis L1 direction.

A case 62 of the stepping motor 6 is gas-tightly fixed to the upper endof the valve housing 1 by welding or the like. A magnet rotor 63 ofwhich outer periphery is multi-magnetized is rotatably provided in thecase 62. A rotor shaft 61 is fixed to the magnet rotor 63. A cylindricalguide 62 a is suspended from a ceiling of the case 62. A cylindricalbearing 64 is provided inside the guide 62 a. An upper end 61B of therotor shaft 61 is rotatably fitted into the bearing 64.

A screw guide 65 attached to the outer periphery of the guide 62 a and amovable stopper 66 screwed into the screw guide 65 are provided in thecase 62. A projection 63 a is formed on the magnet rotor 63. As themagnet rotor 63 is rotated, the projection 63 a pushes the movablestopper 66, so that the movable stopper 66 is moved rotatingly up anddown because the movable stopper 66 is screwed into the screw guide 65.

Owing to this vertical movement of the movable stopper 66, the movablestopper 66 abuts on a stopper 65 a at an upper end of the screw guide65, or a stopper 65 b at a lower end of the screw guide 65 to open orclose the expansion valve 10.

A stator coil 67 is mounted on an outer periphery of the case 62. Thestepping motor 6 as the driving member rotates the magnet rotor 63corresponding to a number of pulses of a pulse signal applied to astator coil (not shown) of the stator coil 67. Owing to the rotation ofthe magnet rotor 63, the rotor shaft 61 is rotated and the rotor shaft61 is moved in the axis L1 direction, so that the valve plug 5 and thevalve holder 4 are moved in the axis L1 direction.

With the above-described structure, the expansion valve 10 operates asfollows. FIG. 2 shows a state that the high pressure refrigerant flowsin from the joint pipe 11 a (a first port 11), then, the flow rate ofthe refrigerant is controlled, and then, the expanded refrigerant flowsout from the joint pipe 12 a (a second port 12). In this case, the firstport 11, the main valve chamber 1A, the high pressure inlets 24, and thesub valve chamber 2A are under high pressure, and the second port 12 isunder low pressure. Therefore, due to the differential pressure of therefrigerant between them, the valve seat 2 is seated around the secondport 12 to close the second port. Then, when the stepping motor 6controls the position of the valve plug 5 in the axis L1 direction, theflow rate of the refrigerant flowing from the sub valve chamber 2A viabetween the valve plug 5 and the valve port 23 is controlled.

On the other hand, the compressor 50 is stopped and the flow pathswitching valve 40 is switched. At this time, the stepping motor 6controls to separate the valve plug 5 from the valve seat 2 (upward),and then the compressor 50 is started again. Thus, when the highpressure refrigerant flows in from the joint pipe 12 a (second port 12),and the refrigerant flows out from the joint pipe 11 a (first port 11),the second port 12 is under high pressure, and the main valve chamber1A, the sub valve chamber 2A, and the first port 11 are under lowpressure. Then, as shown in FIG. 3, the differential pressure separatesthe valve seat 2 from the second port 12, namely, the second port opens.Thus, the refrigerant flows via the second port 12 and the main valvechamber 1A and is discharged from the first port 11.

FIGS. 4A and 4B are schematic views showing a positional relationshipbetween the valve plug 5 and the valve seat 2 when the flow rate iscontrolled, and FIGS. 5A and 5B are schematic views showing a positionalrelationship between the valve plug 5 and the valve seat 2 when theexpansion valve is fully open. Incidentally, because the stepping motor6 is driven by the pulse signals as described above, the number ofrotation corresponds to the number of pulses of the pulse signalsapplied from a state that the valve plug 5 is at the lower end. FIG. 4Ashows a state that the number of the pulse of the stepping motor 6 iszero, and the valve port 23 is closed by the valve plug 5. FIG. 4B showsa state that the number of the pulse is 150. The flow rate is controlledin a range of zero to 480 pulses. FIG. 5A shows a state just before astate shown in FIG. 3 that the compressor 50 is stopped, and the numberof the pulse is 480 pulses to separate the valve plug 5 from the valveport 23. Then, after the flow path switching valve 40 is switched, andthe compressor 50 is started again, the high pressure refrigerant flowsin from the second port 12 and the valve seat 2 is separated from thesecond port 12 as shown in FIG. 5B. Incidentally, when a clearancebetween the valve plug 5 and the valve seat 2 in FIG. 5A is set to “A1”,and a clearance between the valve seat 2 and an area around the secondport 12 is set to “B”, the expansion valve 10 is so designed that A1>B.Therefore, even when the valve seat 2 is separated and the upper end ofthe valve seat 2 abuts on the support member 3, namely, the valve seat 2is at the highest position, there is a clearance A2 between the valveplug 5 and the valve seat 2, and the valve plug 5 never bite the valveport 23.

FIG. 6 is a vertical section view showing the closed compaction valve 10according to the second embodiment. FIG. 7 is a vertical section viewshowing the opened compaction valve 10 according to the secondembodiment. FIG. 8 is a section view taken on line P-P of FIG. 7. FIG. 9is a perspective view showing the valve seat of the compaction valve 10according to the second embodiment. Incidentally, the compaction valve10 of the second embodiment is also used in the refrigeration cycleapparatus of FIG. 1.

This compaction valve 10 of the second embodiment includes a valvehousing 7. A cylindrical main valve chamber 7A is formed in the valvehousing 7. A joint pipe 711 is attached to an inner peripheral wall atone side of the main valve chamber 7A. An end of the joint pipe 711 is afirst port 71 opening on the main valve chamber 7A. Further, a valveseat ring 721 and a joint pipe 722 are attached to an end of the mainvalve chamber 7A at the one side in the axis L1 direction. An end of thevalve seat ring 721 is a second port 72. Incidentally, the valve seatring 721 and the valve housing 7 may be formed integrally with eachother.

A valve seat 8 is arranged in the main valve chamber 7A. The valve seat8 is made by pressing a metal plate, and composed of a circular disk 81perpendicular to the axis L1 of the main valve chamber 7A, and threeguiding plates 82, 83, 84. The guiding plates 82, 83, 84 extends tothree directions from a periphery of the circular disk 81, and extendsvertically parallel to the axis L1 in an L-shape. An inner partsurrounded by the circular disk 81 and the three guiding plates 82, 83,84 is a sub valve chamber 8A. Further, a valve port 81 a communicatingthe sub valve chamber 8A with the second port 72 is formed in the centerof the circular disk 81. As shown in FIG. 8, two guiding plates 83, 84are disposed at both sides of ends of the joint pipe 711 of the firstport 71. These two guiding plates 83, 84 compose a connecting part whichalways connects the sub valve chamber 8A with the first port 71.

Further, as the peripheries of the guiding plate 82, 83, 84 slidablycontact an inside of the main valve chamber 7A, the valve seat 8 isslidable in the axis direction L1 in the main valve chamber 7A. Becausea flow passing area of the valve port 81 a is smaller than that of thefirst port 71, when the refrigerant flows via the second port 72, thecompaction valve 10 is in the full open state as shown in FIG. 7. Thus,when the second port 72 is under high pressure, owing to thedifferential pressure between the second port 72 and the sub valvechamber 8A, the valve seat 8 is moved away from the second port 72(valve seat ring 721).

A supporting member x1 is attached to an opening 7 a at an upper end ofthe valve housing 7. The supporting member x1 is composed of asubstantially cylindrical synthetic-resin-made holder x11, a fittingpart x12 for fitting into the opening 7 a of the valve housing 7, and aring-shaped metallic flange x13. A guide hole x11 a extending in theaxis L1 direction is provided on the holder x11, and a female threadpart x11 b is formed at the upper center of the holder x11. Acylindrical valve holder 44 is fitted with the guide hole x11 a slidablyin the axis L1 direction.

The valve holder 44 is coaxial to the main valve chamber 7A. A valvebody 51 of which end is in a needle shape is fixed to a bottom part atthe sub valve chamber 8A side of the valve holder 44. The valve body 51controls the flow rate of the fluid flowing from the first port 71 tothe second port 72 by increasing or decreasing the opening area of thevalve port 81 a when the valve body 51 and the valve holder 44 movetogether in the sub valve chamber 8A of the valve seat 8 in the axisdirection L1. Incidentally, the valve body 51 is movable between thelowest, full closed position shown in FIG. 6 and the highest, full openposition shown in FIG. 7.

Further, the valve holder 44 is engaged with a rotor spindle 91 of astepping motor 9 as a driving unit. A flange 91 a is integrally formedat a lower end 91A of the rotor spindle 91. This flange 91 a and anupper end of the valve holder 44 sandwich a washer 441. The lower end91A of the rotor spindle 91 is rotatably engaged with an upper end ofthe valve holder 44. Owing to this engagement, the valve holder 44 issupported rotatably in a state that the valve holder 44 is suspendedfrom the rotor spindle 91. Further, in the valve holder 44, a springbearing 442 is disposed movably in the axis direction L1. A compressioncoil spring 443 is interposed between the spring bearing 442 and thevalve body 51, and biased by a specific load. Thus, the spring bearing442 is pushed upward and engaged with the lower end 91A of the rotorspindle 91.

A male thread part 91 b is formed on the rotor spindle 91. This malethread part 91 b is screwed with a female thread part x11 b formed on asupporting member x1. Thus, as the rotor spindle 91 rotates, the rotorspindle 91 is moved in the axis direction L1.

A case 92 of the stepping motor 9 is hermetically fixed to an outercircumferential end of the valve housing 7 by welding or the like. Thecase 92 forms a cylindrical rotor chamber 92A. A magnet rotor 93 ofwhich outer periphery is multipole-polarized is rotatably arranged inthe rotor chamber 92A. The rotor spindle 91 is fixed to the magnet rotor93. Further, a cylindrical guide 92 a is suspended from a ceiling of thecase 92.

Further, a spiral guiding line 95 attached to the outer periphery of theguide 92 a, and a movable stopper 96 screwed with the spiral guidingline 95 are arranged in the case 92. A projection 93 a is formed in themagnet rotor 93. As the magnet rotor 93 rotates, the projection 93 akicks around the movable stopper 96 so that the movable stopper 96 movesrotatingly up and down because the movable stopper 96 is screwed withthe spiral guiding line 95. Then, when the movable stopper 96 contacts astopper 95 b at the lower end of the spiral guiding line 95, the valvestops closing.

Further, a stator coil 97 is arranged at the outer periphery of the case92. When pulse signals are supplied to the stator coil 97, the steppingmotor 9 rotates the magnet rotor 93 corresponding to the number of thepulse signals. Then, owing to the rotation of the magnet rotor 93, therotor spindle 91 integrated with the magnet rotor 93 rotates. As therotor spindle 91 rotates, the rotor spindle 91 moves in the axisdirection L1, and the valve holder 44 and the valve body 51 move in theaxis direction L1.

According to the above configuration, the compaction valve 10 of thesecond embodiment operates as described below. First, the high pressurerefrigerant flows in from the joint pipe 711 (first port 71), and theflow rate of the refrigerant is controlled, then, the expandedrefrigerant flows out from the joint pipe 722 (second port 72). In thiscase, because the first port 71, the main valve chamber 7A, and the subvalve chamber 8A are under high pressure, and the second port 72 isunder low pressure, due to the differential pressure, the valve seat 8is seated on the valve seat ring 721 to close the second port 72. Then,when the stepping motor 9 controls the position of the valve body 51 inthe axis direction L1, the flow rate of the refrigerant flowing from thesub valve chamber 8A to a space between the valve body 51 and the valveport 81 a is regulated.

On the other hand, the compressor 50 is stopped and the flow pathswitching valve 40 is switched. At this time, the stepping motor 9controls to move the valve body 51 far away from the valve seat 8(upward), and the compressor 50 is driven again. Because the valve body51 is separated from the valve seat 8, when the refrigerant flows infrom the joint pipe 722, while the valve seat 8 is seated on the valveseat ring 721, the second port 72 becomes under high pressure, and themain valve chamber 7A, the sub valve chamber 8A, and the first port 71become under low pressure. Then, owing to the differential pressure ofthe refrigerant, the valve seat 8 moves away from the valve seat ring721 (second port 72). Namely, the second port 72 is open. Thus, therefrigerant flows to the first port 71 via the second port 72 and themain valve chamber 7A.

Incidentally, the stepping motor 9 is driven by the pulse signalssimilar to the first embodiment. The flow control is operated in a rangeof 0 pulse to 480 pulses in the flow condition of the refrigerant shownin FIG. 6.

Thus, the expansion valve 10 according to the first and secondembodiments can be both in a full open state (FIG. 3, FIG. 7) not tocontrol the flow rate, and in a semi-closed state (FIG. 2, FIG. 6) tocontrol the flow rate of the refrigerant. Therefore, the two expansionvalves 10 ₁, 10 ₂ in the heat pump type refrigeration cycle apparatusshown in FIG. 1 are realized. Therefore, in the heat pump typerefrigeration cycle apparatus, a large amount of refrigerant flowsthrough the pipe line “a” in both cooling and heating modes, and thepressure loss is reduced.

In the valve seat 2 according to the second embodiment, because a wallfacing the second port 12 is a tapered wall, if a little displacementoccurs when the valve seat 2 seals (is seated on) the valve seat 2, thetapered wall works as the centripetal effect. However, in the valve seat8 according to the second embodiment, because the flat circular diskseals the second port 72, a displacement occurs as a clearance betweenthe valve seat 8 and the valve housing 7 when the valve seat 8 isseated. Thus, after the valve seat 8 is seated and before the flowpressure from the first port 71 to the second port 72 acts, a centeringis performed by positioning the stepping motor 9 at a base position of 0pulse, and by the valve body 51 fitting to the periphery of the valveport 81 a. Further, even if the pressed valve seat of the secondembodiment, when the wall of the circular disk 81 facing the second port72 is formed tapered, the centripetal effect similar to the firstembodiment is attained.

In the above embodiments, the differential pressure moves the valve seataway from the second port. When the differential pressure is small, anelevation of the valve seat may be insufficient, and pressure loss maybe occurred. Therefore, preferably, the valve seat 2 of the firstembodiment is made of resin or light metal such as aluminum. However,when the valve seat 2 is made of resin, if a dust is mixed in the pipearrangement, the valve seat may be abraded remarkably. On the contrary,because the valve seat 8 of the second embodiment is made by pressingthe metal plate, the valve seat 8 is light, and abrasion resistance isincreased.

The expansion valve 10 is so configured to effectively equalize thepressure between the rotor chamber 92A and the main valve chamber 7A forpreventing the malfunction, and preventing a foreign object fromentering the rotor chamber 92A. A configuration of the expansion valve10 will be explained.

FIG. 10 is composed of a partially broken side view (FIG. 10A), a bottomview (FIG. 10B), and a perspective view (FIG. 10C) showing thesupporting member x1 as a first example of the expansion valve 10according to the second embodiment, and a sectional view (FIG. 10D)showing the valve housing 7. A smaller diameter part x12 a is formed onthe fitting part x12 of the supporting member x1 near the flange x13. Asshown in FIG. 10B, the fitting part x12 is formed on a wholecircumference of the fitting part x12, and has a concave shape in aradial direction perpendicular to the axis direction L1. Further, acommunicating path x13 a for communicating with the rotor chamber 92Aand the smaller diameter part x12 a is formed on the flange x13. Fourcommunicating paths x13 a are formed around the axis direction L1. Aninner diameter of the communicating path x13 a is about 1 mm.

An outer diameter φd2 of an outer circumference of the fitting part x12is formed 0.3 mm (specific amount) smaller than an inner diameter φd3 ofan inner circumference of the valve housing 7. Thereby, a 0.15 mm-widthgap x12 b (see FIG. 6) is formed between the outer circumference of thefitting part x12 and the inner circumference of the valve housing 7. Apressure equalizing path communicating the rotor chamber 92A with themain valve chamber 7A is composed of the gap x12 b, the smaller diameterpart x12 a, and the communicating path x13 a.

Owing to a screw feed mechanism composed of the male thread part 91 b ofthe rotor spindle 91 and the female thread part x11 b of the supportingmember x1, similar to the above described, as the magnet rotor 93rotates, the rotor spindle 91 is moved in the axis direction L1.Thereby, the valve body 51 together with the valve holder 44 is moved inthe axis direction L1, and the flow rate of the fluid is controlled.Further, when the valve body 51 is moved, the pressure of the rotorchamber 92A and the main valve chamber 7A are equalized owing to the gapx12 b, the smaller diameter part x12 a, and the communicating path x13a.

A total opening cross-sectional area of the pressure equalizing path inthe flow direction of the refrigerant is respectively set as below inthe gap x12 b, the smaller diameter part x12 a (concave part), and thecommunicating path x13 a. The total opening cross-sectional area of thesmaller diameter part x12 a is sufficiently larger than that of thecommunicating paths x13 a (sum of four paths). The total openingcross-sectional area of the gap x12 b is also larger than that of thecommunicating paths x13 a. Further, as described above, the diameter ofthe communicating path x13 a is about 1 mm, and has a sufficient totalopening cross-sectional area for smoothly equalizing the pressurebetween the rotor chamber 92A and the main valve chamber 7A.Accordingly, the total pressure equalizing path can smoothly equalizethe pressure between the rotor chamber 92A and the main valve chamber7A. In contrast, the width of the gap x12 b is 0.15 mm and sufficientlysmaller than the diameter φd1 about 1 mm of the communicating path x13a, thereby a foreign object is prevented from entering the rotor chamber92A from the main valve chamber 7A.

Namely, the gap x12 b is composed of the outer circumference of thefitting part x12 and the inner circumference of the valve housing 7 ofwhich diameters are several orders of magnitude larger than the diameterφd1 of the communicating path x13 a (about 1 mm). Therefore, whilemaking the width of the gap x12 b smaller, the total openingcross-sectional area can become sufficiently larger. Thus, both thesmooth pressure equalization and the prevention of entry of foreignobjects can be attained at the same time.

FIG. 11 is composed of a partially broken side view (FIG. 11A) and abottom view (FIG. 11B) showing the supporting member x2 as a secondexample of the expansion valve 10 of the second embodiment. FIG. 12 iscomposed of a partially broken side view (FIG. 12A) and a bottom view(FIG. 12B) showing the supporting member x3 as a third example of theexpansion valve 10 of the second embodiment.

In the second example shown in FIG. 11, the supporting member x2 isattached to the opening 7 a at the upper end of the valve housing 7. Thesupporting member x2 is composed of a substantially cylindricalsynthetic-resin-made holder x21, a fitting part x22 for fitting into theopening 7 a of the valve housing 7, and a ring-shaped metallic flangex23. A guide hole x21 a extending in the axis L1 direction is providedon the holder x21, and a female thread part x21 b is formed at the uppercenter of the holder x21. The cylindrical valve holder 44 is fitted withthe guide hole x21 a slidably in the axis L1 direction. Further, themale thread part 91 b of the rotor spindle 91 is screwed with the femalethread part x21 b of the supporting member x2. The screw feed mechanismis composed of the male thread part 91 b of the rotor spindle 91 and thefemale thread part x21 b of the supporting member x2.

A concave part x22 a is formed on the fitting part x22 of the supportingmember x2 at the flange x23 side. Four concave parts x22 a are arrangedaround the fitting part x22 in a hollow shape radially perpendicular tothe axis direction L1. Further, a communicating path x23 a forcommunicating with the rotor chamber 92A and the concave part x22 a isformed on the flange x23. Four communicating paths x13 a are formedaround the axis direction L1. An inner diameter φd1 of the communicatingpath x23 a is about 1 mm.

The relationship between the outer diameter φd2 of an outercircumference of the fitting part x22 and the inner diameter φd3 of theinner circumference of the valve housing 7 is the same as the firstexample. A 0.15 mm-width gap x22 b (FIG. 11A) is formed between theouter circumference of the fitting part x22 and the inner circumferenceof the valve housing 7. A pressure equalizing path communicating therotor chamber 92A with the main valve chamber 7A is composed of the gapx22 b, the concave part x22 a, and the communicating path x23 a.Further, the operation is the same as the first example. When the valvebody 51 is moved, the pressure of the rotor chamber 92A and the mainvalve chamber 7A is equalized owing to the gap x22 b, the concave partx22 a, and the communicating path x23 a.

In this second example, the relationship of the total openingcross-sectional area of the gap x22 b, the concave part x22 a, and thecommunicating path x23 a is similar to that of the gap x12 b, thesmaller diameter part x12 a, and the communicating path x13 a in thefirst example. Thereby, similar to the first example, both the smoothpressure equalization with the total pressure equalizing path and theprevention of entry of foreign objects with the gap x22 b can beattained at the same time.

In the third example shown in FIG. 12, the supporting member x3 isattached to the opening 7 a at the upper end of the valve housing 7. Thesupporting member x3 is composed of a substantially cylindricalsynthetic-resin-made holder x31, a fitting part x32 for fitting into theopening 7 a of the valve housing 7, and a ring-shaped metallic flangex33. A guide hole x31 a extending in the axis L1 direction is providedon the holder x31, and a female thread part x31 b is formed at the uppercenter of the holder x31. The cylindrical valve holder 44 is fitted withthe guide hole x31 a slidably in the axis L1 direction. Further, themale thread part 91 b of the rotor spindle 91 is screwed with the femalethread part x31 b of the supporting member x3. The screw feed mechanismis composed of the male thread part 91 b of the rotor spindle 91 and thefemale thread part x31 b of the supporting member x3.

A concave part x32 a is formed on the fitting part x32 of the supportingmember x3 at the flange x33 side. This concave part x32 a is formed on awhole circumference of the fitting part x32 and has a concave shape in aradial direction perpendicular to the axis direction L1. An inner wallof the concave part x32 a at the main valve chamber 7A side is formed ina taper wall x32 a 1 in a manner that a sectional area perpendicular tothe axis direction L1 becomes larger toward the rotor chamber 92A. Acommunicating path x33 a for communicating with the rotor chamber 92Aand the concave part x32 a is formed on the flange x33. Fourcommunicating paths x33 a are formed around the axis direction L1. Aninner diameter φd1 of the communicating path x33 a is about 1 mm.

The relationship between the outer diameter φd2 of an outercircumference of the fitting part x32 and the inner diameter φd3 of theinner circumference of the valve housing 7 is the same as the firstexample. A 0.15 mm-width gap x32 b (FIG. 12A) is formed between theouter circumference of the fitting part x32 and the inner circumferenceof the valve housing 7. A pressure equalizing path communicating therotor chamber 92A with the main valve chamber 7A is composed of the gapx32 b, the concave part x32 a, and the communicating path x33 a.Further, the operation is the same as the first example. When the valvebody 51 is moved, the pressure of the rotor chamber 92A and the mainvalve chamber 7A is equalized owing to the gap x32 b, the concave partx32 a, and the communicating path x33 a.

In this third example, the relationship of the total openingcross-sectional area of the gap x32 b, the concave part x32 a, and thecommunicating path x33 a is similar to that of the gap x12 b, thesmaller diameter part x12 a, and the communicating path x13 a in thefirst example. Thereby, similar to the first example, both the smoothpressure equalization with the total pressure equalizing path and theprevention of entry of foreign objects with the gap x32 b can beattained at the same time.

Further, owing to the taper wall x32 a 1 of the concave part x32 a, thesectional area of the concave part is larger toward the rotor chamber92A, thereby loss factor can be reduced, and the pressure loss of thepressure equalizing path can be reduced.

FIG. 13 is composed of a partially broken side view (FIG. 13A) and abottom view (FIG. 13B) showing a supporting member x4 of a conventionalexpansion valve. The conventional supporting member x4 is composed of aholder x41, a fitting part 42, and a flange x43, and a guide hole x41 aand a female thread part x41 b are formed on the holder x41, which aresubstantially similar to the previous embodiment. Pressure equalizationholes x42 a, x43 a penetrating straight from a valve chamber 10A to therotor chamber 92A is formed on the fitting part x42 and the flange x43,which is different from the previous embodiment. Four pressureequalization holes x42 a, x43 a are formed around the axis direction L1.An inner diameter φd1 of each of the pressure equalization holes x42 a,x43 a is about 1 mm.

Because the inner diameter φd1 of each of the conventional pressureequalization holes x42 a, x43 a is defined by a diameter of a drill fordrilling a hole, there is a limit to minimize the diameter φd1=W1.Therefore, there is a limit to prevent the foreign objects fromentering. In contrast, the width W2 of the gap x12 b, x22 b, x32 b ofthe first to third examples is:W2=(φd3−φd2)/2.

Namely, by adjusting the outer diameter φd2 of the fitting parts x12,x22, x32 with respect to the inner diameter φd3 of the valve housing 7,the width W2 of the gaps x12 b, x22 b, x32 b is easily minimized, andthe entry of the foreign objects can be prevented.

Further, an opening area A1 of the conventional pressure equalizationholes x42 a, x43 a is:A1=π(φd1/2)² n (in the previous example, n=4)

In contrast, an opening area A2 of the outer circumference of the gapsx12 b, x22 b, x32 b is:A2=π[(φd3/2)²−(φd/2)²]

Namely, by adjusting the outer diameter φd2 of the fitting parts x12,x22, x32, it is possible that A1 is several orders of magnitude smallerthan A2, while W1 is several orders of magnitude larger than W2. Whilepreventing the foreign object from entering, high pressure equalizationeffect can be attained.

In the first to third examples, φd2 is 0.3 mm smaller than φd3, and thewidth of the gaps x12 b, x22 b, x32 b is 0.15 mm. However, φd2 may be0.1 to 0.4 mm smaller than φd3, and the width of the gaps x12 b, x22 b,x32 b may be 0.05 to 0.2 mm.

In the first to third examples, the communicating path (×13a, x23 a, x33a) communicates with the gap (x12 b, x22 b, x23 b) via the smallerdiameter part or the concave part (x12 a, x22 a, x32 a). However, byeliminating the smaller diameter part or the concave part (x12 a, x22 a,x32 a), and by forming the communicating path (x13 a, x23 a, x33 a)slightly displaced outward in the radial direction, the communicatingpath (x13 a, x23 a, x33 a) and the gap (x12 b, x22 b, x23 b) maydirectly communicate with each other.

Incidentally, in general, the air handling unit is provided with a filerfor catching the foreign objects in the unit. A mesh size of this filteris generally 80 to 120 mesh (80 to 120 mesh per inch) both domestic andoverseas. Therefore, a gap for preventing the foreign objects fromentering the rotor chamber from the main valve chamber during therefrigerating cycle is about 80 to 120 mesh (for example, 0.15 mm), andeach of the gaps x12 b, x22 b, x23 b of the first to third examples isaccordingly 0.15 mm width.

Further, the embodiments of which gap width is about 80 to 120 mesh hasbeen described. However, the gap width may be adjusted to the size ofthe foreign object to be prevented from entering the rotor chamber, andthe present invention is not limited to 80 to 120 mesh.

When the foreign objects in the air handling unit are extremely small,it is necessary to change the mesh size of the filter smaller than 120mesh. When the mesh size of the filter is smaller, an area of the wirecomposing the mesh is larger, and an area to pass the fluid is reduced.Thereby, pressure loss at the filter is increased. Accordingly, it isnot preferable to make the mesh size of the filter smaller because thepressure loss of the air handling unit is increased.

So, when the gap of the expansion valve becomes smaller than 0.15 mm,the extremely small foreign objects can be caught by the gap, thereby itbecomes unnecessary to make the mesh size of the filter very small.Resultingly, the pressure loss of the air handling unit can be reduced,and a great amount of refrigerant can be passed. Namely, when the airhandling unit is provided with the filter, the filter does not block theflow of the refrigerant and the air handling unit can pass the greatamount of refrigerant.

Although the present invention has been fully described by way ofexample with reference to the accompanying drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless otherwise such changes andmodifications depart from the scope of the present invention hereinafterdefined, they should be construed as being included therein.

1. An expansion valve for controlling a flow rate of a refrigerant in afirst flow direction of the refrigerant and for discharging therefrigerant in a second flow direction, said expansion valve comprising:a valve housing having a first port communicating with a cylindricalmain valve chamber and with a side part of the main valve chamber, and asecond port communicating with an end of the main valve chamber in anaxial direction thereof; a valve seat slidably disposed in the mainvalve chamber in the axial direction of the main valve chamber, andhaving a sub valve chamber opposed to the second port in the main valvechamber, a valve port for connecting the sub valve chamber to the secondport, and a connecting hole for always connecting the sub valve chamberto the first port; a valve plug for opening and closing the valve portof the valve seat by moving relative to the valve seat in the axialdirection; and a driving member for driving the valve plug in the axialdirection, wherein in a case that the first port is under highrefrigerant pressure and the second port is under low refrigerantpressure, a flow rate of the refrigerant flowing from the sub valvechamber through a path between the valve plug and the valve port iscontrolled by closing the second port with the valve seat seated aroundthe second port due to differential pressure between the first andsecond ports and by controlling a position of the valve plug in theaxial direction with the driving member, and wherein in a case that thefirst port is under low refrigerant pressure and the second port isunder high refrigerant pressure by making the refrigerant flowreversely, the refrigerant is discharged to the first port via thesecond port and the main valve chamber, said second port is opened bymoving the valve plug in the axial direction with the driving member andby separating the valve seat from the second port due to thedifferential pressure between the second and first ports, wherein thedriving member is composed of a rotor case fixed around an opening ofthe valve housing opposite to the first port to form a cylindrical rotorchamber, a rotor having a rotor shaft in the axial direction of therotor chamber and the main valve chamber and rotatably and movablydisposed in the rotor chamber in the axis direction, and a stator coilattached to an outer circumference of the rotor case and driving therotor, and the valve body is disposed at the rotor shaft near the valveseat, said driving member further including a supporting member fixed tothe opening of the valve housing for separating the main valve chamberfrom the rotor chamber and for supporting the rotor shaft of the rotor,and configured to control an opening of the valve port by moving therotor and the rotor shaft in the axial direction with a screw mechanismof the supporting member and the rotor shaft using a rotation of therotor, and configured to equalize the pressure between the main valvechamber and the rotor chamber when the rotor is moved in the axialdirection using a pressure equalizing path communicating with the mainvalve chamber and the rotor chamber, wherein the supporting memberincludes: a fitting part for fitting into the opening of the valvehousing; and a flange part fixed to an end around the circumference ofthe opening of the valve housing, wherein a communicating path openingat the rotor chamber side is formed on the flange, and an outer diameterof the fitting part is a specific amount smaller than an inner diameterof an inner circumference of the valve housing, wherein a concave partconcaved in a radial direction perpendicular to the axial direction isformed on the fitting part at the flange side, and a gap between theouter circumference of the fitting part and the inner circumference ofthe valve housing communicates with the communicating path via theconcave part, and wherein the pressure equalizing path is composed ofthe gap between the outer circumference of the fitting part and theinner circumference of the valve housing and the communicating path.